| Message ID | 20240319104714.1178-1-chenhx.fnst@fujitsu.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | NFSD: nfsctl: remove read permission of filehandle | expand |
On Tue, 2024-03-19 at 18:47 +0800, Chen Hanxiao wrote: > As write_filehandle can't accept zero-bytes writting, > remove read permission of /proc/fs/nfsd/filehandle > > Signed-off-by: Chen Hanxiao <chenhx.fnst@fujitsu.com> > --- > fs/nfsd/nfsctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c > index ecd18bffeebc..da1387f1e30a 100644 > --- a/fs/nfsd/nfsctl.c > +++ b/fs/nfsd/nfsctl.c > @@ -1346,7 +1346,7 @@ static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc) > &transaction_ops, S_IWUSR|S_IRUSR}, > [NFSD_FO_UnlockFS] = {"unlock_filesystem", > &transaction_ops, S_IWUSR|S_IRUSR}, > - [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR}, > + [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR}, > [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR}, > [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR}, > [NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO}, I don't think we can do this. mountd does this to get the rootfh for an exported fs and it'll probably start failing if it can't open that file for read: f = open("/proc/fs/nfsd/filehandle", O_RDWR); That write_filehandle interface sure is weird though. Could we get rid of it by teaching cache_get_filehandle how to use name_to_handle_at instead? That would be a lot cleaner and would get rid of yet another dependency on /proc/fs/nfsd.
> -----邮件原件----- > 发件人: Jeff Layton <jlayton@kernel.org> > 发送时间: 2024年3月19日 21:09 > 收件人: Chen, Hanxiaochenhx.fnst@fujitsu.com>; Chuck Lever > <chuck.lever@oracle.com>; Neil Brown <neilb@suse.de>; Olga Kornievskaia > <kolga@netapp.com>; Dai Ngo <Dai.Ngo@oracle.com>; Tom Talpey > <tom@talpey.com> > 抄送: linux-nfs@vger.kernel.org > 主题: Re: [PATCH] NFSD: nfsctl: remove read permission of filehandle > > On Tue, 2024-03-19 at 18:47 +0800, Chen Hanxiao wrote: > > As write_filehandle can't accept zero-bytes writting, > > remove read permission of /proc/fs/nfsd/filehandle > > > > Signed-off-by: Chen Hanxiao <chenhx.fnst@fujitsu.com> ... > > > I don't think we can do this. mountd does this to get the rootfh for an > exported fs and it'll probably start failing if it can't open that file > for read: > > f = open("/proc/fs/nfsd/filehandle", O_RDWR); > > That write_filehandle interface sure is weird though. Could we get rid > of it by teaching cache_get_filehandle how to use name_to_handle_at > instead? That would be a lot cleaner and would get rid of yet another > dependency on /proc/fs/nfsd. name_to_handle_at return struct file_handle cache_get_filehandle return hexed struct knfsd_fh Could you please give some hints on how to convert from file_handle. f_handle to knfsd_fh.fh_raw? Regards, - Chen > -- > Jeff Layton <jlayton@kernel.org>
On Wed, 2024-03-20 at 15:49 +0000, Hanxiao Chen (Fujitsu) wrote: > > > -----邮件原件----- > > 发件人: Jeff Layton <jlayton@kernel.org> > > 发送时间: 2024年3月19日 21:09 > > 收件人: Chen, Hanxiaochenhx.fnst@fujitsu.com>; Chuck Lever > > <chuck.lever@oracle.com>; Neil Brown <neilb@suse.de>; Olga Kornievskaia > > <kolga@netapp.com>; Dai Ngo <Dai.Ngo@oracle.com>; Tom Talpey > > <tom@talpey.com> > > 抄送: linux-nfs@vger.kernel.org > > 主题: Re: [PATCH] NFSD: nfsctl: remove read permission of filehandle > > > > On Tue, 2024-03-19 at 18:47 +0800, Chen Hanxiao wrote: > > > As write_filehandle can't accept zero-bytes writting, > > > remove read permission of /proc/fs/nfsd/filehandle > > > > > > Signed-off-by: Chen Hanxiao <chenhx.fnst@fujitsu.com> > ... > > > > > > I don't think we can do this. mountd does this to get the rootfh for an > > exported fs and it'll probably start failing if it can't open that file > > for read: > > > > f = open("/proc/fs/nfsd/filehandle", O_RDWR); > > > > That write_filehandle interface sure is weird though. Could we get rid > > of it by teaching cache_get_filehandle how to use name_to_handle_at > > instead? That would be a lot cleaner and would get rid of yet another > > dependency on /proc/fs/nfsd. > > name_to_handle_at return struct file_handle > cache_get_filehandle return hexed struct knfsd_fh > > Could you please give some hints on how to convert from file_handle. f_handle to knfsd_fh.fh_raw? > I started looking at this yesterday. knfsd_fh is mostly constructed in fh_compose. The exportfs_encode_fh call is in _fh_update. If we look at the comments over knfsd_fh, it explains pretty well what we need to fill out: fh_version : should always be 1 fh_auth_type: always 0 fh_fsid_type: this is the tricky part (see below) fh_fileid_type: returned by name_to_handle_at fh_fsid: fsid concatenated with the fileid for the inode name_to_handle_at should be able to fill out the fileid portion of the knfsd_fh. The harder part is: how do we get the fh_fsid_type and its content? The types are shown here: * The fsid_type identifies how the filesystem (or export point) is * encoded. * Current values: * 0 - 4 byte device id (ms-2-bytes major, ls-2-bytes minor), 4byte inode number * NOTE: we cannot use the kdev_t device id value, because kdev_t.h * says we mustn't. We must break it up and reassemble. * 1 - 4 byte user specified identifier * 2 - 4 byte major, 4 byte minor, 4 byte inode number - DEPRECATED * 3 - 4 byte device id, encoded for user-space, 4 byte inode number * 4 - 4 byte inode number and 4 byte uuid * 5 - 8 byte uuid * 6 - 16 byte uuid * 7 - 8 byte inode number and 16 byte uuid The kernel decides this in set_version_and_fsid_type, so I suppose we could try to replicate that logic in userland. There is the problem though of what to do about exports with the fsid= option set. That's tougher to determine from userland, but maybe we can somehow get that from the export record? That's about as far as I got with it yesterday...
Hi, Jeff
I wrote a POC patch, use name_to_handle_at to get nfs root filehandle
instead of /proc/fs/nfsd/filehandle.
I did some simple tests and it works.
Pls check the POC patch below:
---
support/export/cache.c | 95 +++++++++++++++++++++++++++++++++++++++++-
1 file changed, 93 insertions(+), 2 deletions(-)
diff --git a/support/export/cache.c b/support/export/cache.c
index 6c0a44a3..adecac2e 100644
--- a/support/export/cache.c
+++ b/support/export/cache.c
@@ -43,6 +43,25 @@
#include "blkid/blkid.h"
#endif
+#define NFS4_FHSIZE 128
+
+struct knfsd_fh {
+ unsigned int fh_size; /*
+ * Points to the current size while
+ * building a new file handle.
+ */
+ union {
+ char fh_raw[NFS4_FHSIZE];
+ struct {
+ uint8_t fh_version; /* == 1 */
+ uint8_t fh_auth_type; /* deprecated */
+ uint8_t fh_fsid_type;
+ uint8_t fh_fileid_type;
+ uint32_t fh_fsid[]; /* flexible-array member */
+ };
+ };
+};
+
enum nfsd_fsid {
FSID_DEV = 0,
FSID_NUM,
@@ -1827,8 +1846,8 @@ int cache_export(nfs_export *exp, char *path)
* read filehandle <&0
* } <> /proc/fs/nfsd/filehandle
*/
-struct nfs_fh_len *
-cache_get_filehandle(nfs_export *exp, int len, char *p)
+static struct nfs_fh_len *
+cache_get_filehandle_by_proc(nfs_export *exp, int len, char *p)
{
static struct nfs_fh_len fh;
char buf[RPC_CHAN_BUF_SIZE], *bp;
@@ -1862,6 +1881,78 @@ cache_get_filehandle(nfs_export *exp, int len, char *p)
return &fh;
}
+static struct nfs_fh_len *
+cache_get_filehandle_by_name(nfs_export *exp, char *name)
+{
+ static struct nfs_fh_len fh;
+ struct {
+ struct file_handle fh;
+ unsigned char handle[128];
+ } file_fh;
+ char buf[RPC_CHAN_BUF_SIZE] = {0};
+ char *mesg = buf;
+ int len, mnt_id;
+ unsigned int e_fsid;
+ struct knfsd_fh kfh;
+ char u[16];
+
+ memset(fh.fh_handle, 0, sizeof(fh.fh_handle));
+
+ file_fh.fh.handle_bytes = 128;
+ if (name_to_handle_at(AT_FDCWD, name, &file_fh.fh, &mnt_id, 0) < 0)
+ return NULL;
+
+ memset(fh.fh_handle, 0, sizeof(fh.fh_handle));
+ memset(&kfh, 0, sizeof(struct knfsd_fh));
+ kfh.fh_version = 1;
+ kfh.fh_auth_type = 0;
+ e_fsid = exp->m_export.e_fsid;
+
+ if (e_fsid > 0) {
+ len = 12;
+ fh.fh_size = 8;
+ kfh.fh_size = 12;
+ kfh.fh_fsid_type = 1;
+ kfh.fh_fsid[0] = e_fsid;
+ } else {
+ len = file_fh.fh.handle_bytes + 8;
+ fh.fh_size = file_fh.fh.handle_bytes;
+ kfh.fh_size = file_fh.fh.handle_bytes + sizeof(kfh.fh_size);
+ kfh.fh_fsid_type = FSID_UUID16_INUM;
+ if (file_fh.fh.handle_bytes <= 12) {
+ kfh.fh_fsid[0] = *(uint32_t *)file_fh.fh.f_handle;
+ kfh.fh_fsid[1] = 0;
+ } else {
+ kfh.fh_fsid[0] = *(uint32_t *)file_fh.fh.f_handle;
+ kfh.fh_fsid[1] = *((uint32_t *)file_fh.fh.f_handle + 1);
+ }
+ }
+ kfh.fh_fileid_type = 0; // FILEID_ROOT
+
+ qword_addhex(&mesg, &len, kfh.fh_raw, kfh.fh_size);
+ mesg = buf;
+ len = qword_get(&mesg, (char *)fh.fh_handle, NFS3_FHSIZE);
+ if (e_fsid == 0) {
+ len = 16;
+ uuid_by_path(name, 0, 16, u);
+ memcpy((char *)fh.fh_handle+12, u, 16);
+ fh.fh_size += 16;
+ }
+
+ return &fh;
+}
+
+struct nfs_fh_len *
+cache_get_filehandle(nfs_export *exp, int len, char *p)
+{
+ struct nfs_fh_len *fh;
+ fh = cache_get_filehandle_by_name(exp, p);
+ if (!fh)
+ fh = cache_get_filehandle_by_proc(exp, len, p);
+
+ return fh;
+}
+
/* Wait for all worker child processes to exit and reap them */
void
cache_wait_for_workers(char *prog)
On Wed, 2024-03-27 at 14:40 +0800, Chen Hanxiao wrote: > Hi, Jeff > > I wrote a POC patch, use name_to_handle_at to get nfs root filehandle > instead of /proc/fs/nfsd/filehandle. > > I did some simple tests and it works. > > Pls check the POC patch below: > --- > support/export/cache.c | 95 +++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 93 insertions(+), 2 deletions(-) > Very cool! I do think this is the basic direction we want to go with revising how mountd gets its filehandles. > diff --git a/support/export/cache.c b/support/export/cache.c > index 6c0a44a3..adecac2e 100644 > --- a/support/export/cache.c > +++ b/support/export/cache.c > @@ -43,6 +43,25 @@ > #include "blkid/blkid.h" > #endif > > +#define NFS4_FHSIZE 128 > + > +struct knfsd_fh { > + unsigned int fh_size; /* > + * Points to the current size while > + * building a new file handle. > + */ > + union { > + char fh_raw[NFS4_FHSIZE]; > + struct { > + uint8_t fh_version; /* == 1 */ > + uint8_t fh_auth_type; /* deprecated */ > + uint8_t fh_fsid_type; > + uint8_t fh_fileid_type; > + uint32_t fh_fsid[]; /* flexible-array member */ > + }; > + }; > +}; > + This is a large departure from how this has worked in the past. Before this, userland could always treat a knfsd_fh as opaque. With this change though, knfsd_fh will need to be part of the kernel's ABI, and we'll need to be very careful about future changes to the FH format (not that we're planning any). I think we probably ought to start by moving the definitions of knfsd_fh and its component parts into a UAPI header that nfs-utils could then use. For now, we can add duplicate definitions like above for when the case where they aren't defined in UAPI headers. > enum nfsd_fsid { > FSID_DEV = 0, > FSID_NUM, Side note: I wonder if some of the nfsd_fsid values can (effectively) be deprecated these days? I don't think we really use FSID_DEV anymore at all, do we? > @@ -1827,8 +1846,8 @@ int cache_export(nfs_export *exp, char *path) > * read filehandle <&0 > * } <> /proc/fs/nfsd/filehandle > */ > -struct nfs_fh_len * > -cache_get_filehandle(nfs_export *exp, int len, char *p) > +static struct nfs_fh_len * > +cache_get_filehandle_by_proc(nfs_export *exp, int len, char *p) > { > static struct nfs_fh_len fh; > char buf[RPC_CHAN_BUF_SIZE], *bp; > @@ -1862,6 +1881,78 @@ cache_get_filehandle(nfs_export *exp, int len, char *p) > return &fh; > } > > +static struct nfs_fh_len * > +cache_get_filehandle_by_name(nfs_export *exp, char *name) > +{ > + static struct nfs_fh_len fh; > + struct { > + struct file_handle fh; > + unsigned char handle[128]; > + } file_fh; > + char buf[RPC_CHAN_BUF_SIZE] = {0}; > + char *mesg = buf; > + int len, mnt_id; > + unsigned int e_fsid; > + struct knfsd_fh kfh; > + char u[16]; > + > + memset(fh.fh_handle, 0, sizeof(fh.fh_handle)); > + > + file_fh.fh.handle_bytes = 128; > + if (name_to_handle_at(AT_FDCWD, name, &file_fh.fh, &mnt_id, 0) < 0) > + return NULL; > + > + memset(fh.fh_handle, 0, sizeof(fh.fh_handle)); > + memset(&kfh, 0, sizeof(struct knfsd_fh)); > + kfh.fh_version = 1; > + kfh.fh_auth_type = 0; > + e_fsid = exp->m_export.e_fsid; > + > + if (e_fsid > 0) { > + len = 12; > + fh.fh_size = 8; > + kfh.fh_size = 12; > + kfh.fh_fsid_type = 1; > + kfh.fh_fsid[0] = e_fsid; > + } else { > + len = file_fh.fh.handle_bytes + 8; > + fh.fh_size = file_fh.fh.handle_bytes; > + kfh.fh_size = file_fh.fh.handle_bytes + sizeof(kfh.fh_size); > + kfh.fh_fsid_type = FSID_UUID16_INUM; Note that we will need to deal with NFSv2 here too. It has 32-byte filehandles, and so we likely can't use FSID_UUID16_INUM for those. > + if (file_fh.fh.handle_bytes <= 12) { > + kfh.fh_fsid[0] = *(uint32_t *)file_fh.fh.f_handle; > + kfh.fh_fsid[1] = 0; > + } else { > + kfh.fh_fsid[0] = *(uint32_t *)file_fh.fh.f_handle; > + kfh.fh_fsid[1] = *((uint32_t *)file_fh.fh.f_handle + 1); > + } > + } > + kfh.fh_fileid_type = 0; // FILEID_ROOT > + > + qword_addhex(&mesg, &len, kfh.fh_raw, kfh.fh_size); > + mesg = buf; > + len = qword_get(&mesg, (char *)fh.fh_handle, NFS3_FHSIZE); We may need to pass to this function what version of NFS MNT request was sent so that we know what sort of FH is needed here. > + if (e_fsid == 0) { > + len = 16; > + uuid_by_path(name, 0, 16, u); > + memcpy((char *)fh.fh_handle+12, u, 16); > + fh.fh_size += 16; > + } > + > + return &fh; > +} > + > +struct nfs_fh_len * > +cache_get_filehandle(nfs_export *exp, int len, char *p) > +{ > + struct nfs_fh_len *fh; > + fh = cache_get_filehandle_by_name(exp, p); > + if (!fh) > + fh = cache_get_filehandle_by_proc(exp, len, p); > + > + return fh; > +} > + > /* Wait for all worker child processes to exit and reap them */ > void > cache_wait_for_workers(char *prog) This looks like a great start -- nice work! There are a number of more obscure corner-cases that we'll need to deal with, but this does look like a promising direction.
diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index ecd18bffeebc..da1387f1e30a 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1346,7 +1346,7 @@ static int nfsd_fill_super(struct super_block *sb, struct fs_context *fc) &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_FO_UnlockFS] = {"unlock_filesystem", &transaction_ops, S_IWUSR|S_IRUSR}, - [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR|S_IRUSR}, + [NFSD_Fh] = {"filehandle", &transaction_ops, S_IWUSR}, [NFSD_Threads] = {"threads", &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_Pool_Threads] = {"pool_threads", &transaction_ops, S_IWUSR|S_IRUSR}, [NFSD_Pool_Stats] = {"pool_stats", &pool_stats_operations, S_IRUGO},
As write_filehandle can't accept zero-bytes writting, remove read permission of /proc/fs/nfsd/filehandle Signed-off-by: Chen Hanxiao <chenhx.fnst@fujitsu.com> --- fs/nfsd/nfsctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)